DESCRIPTION: This project will investigate the genetic and epigenetic changes that occur during spontaneous transformation and tumor development in the WB-F344 liver stem-like epithelial cell line. Current data indicates that precursor cells are important targets during hepatocarcinogenesis, and transformed derivatives of WB-F344 cells produce a variety of phenotypes, including hepatocellular carcinomas, adenocarcinomas, hepatoblastomas, and undifferentiated spindle-cell tumors. The author hypothesizes that the genome becomes unstable during spontaneous malignant transformation, leading to aberrations in cellular DNA content and integrity. He predicts that the genomic instability that occurs during transformation causes aberrations in gene expression that allow the transformed cell to avoid cell cycle control and acquire autonomous replication potential, ultimately culminating in the formation of a tumor. The first goal of this proposal is to identify the mechanisms of genomic instability leading to fluctuations in DNA content in the WB-F344 cells during spontaneous transformation, and to identify the minimal genetic-epigenetic changes that are needed for malignant transformation. He will study the mechanisms of genomic instability in spontaneous transformants of WB-F344 by examining chromosomal ultrastructure during the transformation process by karyotype analysis and comparative genomic hybridization (CGH). The second goal is to evaluate the transforming potential of establishment of autocrine growth loops in normal, low-passage WB-F344 cells. This goal will be accomplished by characterizing tumor cell lines which have established autocrine loops, and by creating autocrine loops in otherwise normal, low-passage WB-F344 cells.